Control system for a cycloid propeller for ships

ABSTRACT

A servo motor controlled by a speed control lever and a servo motor controlled by a steering wheel adjust the position of the control point of the pivoted blades of a cycloid propeller in two directions. The control connection between the lever and the servo motor controlled thereby includes a first signal transmitter and the control connection between the wheel and the servo motor controlled thereby includes a second signal transmitter. The signal provided by the first signal transmitter is controlled as a function of a function generator supplied with the signal provided by the second transmitter.

United States Patent Fork et al.

[54] CONTROL SYSTEM FOR A CYCLOID PROPELLER FOR SHIPS [72] Inventors:Kurt Fork, Frauenaurach; Werner Fork, Bremen-Arsten, both of Germany[73] Assignee: Siemens Aktiengesellschaft, Berlin, Munich, Germany 22Filed: Junel5 l97l 21 Appl.No.:153,210

[30] Foreign Application Priority Data June 18, 1970 Germany ..P 20 29995.0

52] us. Cl 416/111 [51] Int. Cl. ..B63h 1/10 [58] Field of Search..4l6/108, 110, Ill

[56] References Cited UNITED STATES PATENTS 3/1966 Baer ..4l6/108 ux[451 Dec. 5, 1972 FOREIGN PATENTS OR APPLICATIONS 898,406 11/1953Germany ..416/108 Primary Examiner-Everette A. Powell, Jr. Attorney-CurtM. Avery et al.

[57] I ABSTRACT A servo motor controlled by a speed control lever and aservo motor controlled by a steering wheel adjust the position vof thecontrol point of the pivoted blades of a cycloid propeller in twodirections. The control connection between the lever and the servo motorcontrolled thereby includes a first signal transmitter and the controlconnection between the wheel and the servo motor controlled therebyincludes a second signal transmitter. The signal provided by the firstsignal transmitter is controlled as a function of a function generatorsupplied with the signal provided by the second transmitter.

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CQNThUlL SYSTEM FOR A CYCLOID PROPELLER FOR SHIPS DESCRIPTION OF THEINVENTION The invention relates to a control system for a cycloidpropeller. More particularly, the invention relates to a control systemfor a cycloid propeller, especially for ships, in which a servo motorcontrolled by a speed controllever and a servo motor controlled by a lo'pivot bearings and during a revolution of the wheel structure arecontrolled approximately so that the normal to the blade surface,erected 'on the axis. of rotation, always goes through one and the samepoint, the so-calied control point. This control point can be shiftedaround as to its position relative to the axis of the wheel structure bymeans of a control stick in order to change the speed and the directionof travel or steer ing angle of the ship. This purpose is served by theservo motors'which are controlled by the speed control lever and thesteering wheel and which adjust the position of the control point of thepivoted blades in two mutually perpendicular directions via a bladedrive linkage. In the known type of structure of cycloid propellers, asdescribed, for example, in German Pat. No. 709,545, only the speedcomponent is controlled by one servo motor and only the steeringcomponent is controlled by the other servo motor.

if, for example, the control point is situated on the axis of rotationof the wheel structure, which is driven at constant speed, all thepivoted blades remain at rest relative to the wheel structure as saidwheel structure rotates. The developed propeller thrust is zero. if thecontrol point is displaced relative to the axis of rotation, that is, ifit is eccentric to said axis of rotation, the pivoted blades carry outan oscillatory motion, whereby positive thrust forces are produced atthe cycloid propeller. The magnitude of the positive thrust forces isthe result of the selected eccentricity of the control point. Thedirection of the positive thrust forces results from the direction ofthe eccentricity. By geometric addition of the positioning travel of thetwo servo motors, thrust forces may be obtained at any desired anglerelative to the ships axis. The direction of the eccentricity of thecontrol point forms a definite angle with respect to the direction ofthe thrust developed by the cycloid propeller, which depends on thedesign of the blade drive linkage.

If it is desired to adjust by means of a servo motor an eccentricity ofthe control point which would result in a thrust along the longitudinalaxis of the ship, such servo motor would have to form a definite angle,independent of the type of blade drive linkage, relative to thelongitudinal axis of the ship. Thus, it has heretofore been necessary indesigning a cycloid propeller to take such angle into consideration. Ithas also been necessary to consider the arrangement of the drive motorin the ship and to arrange the servo motors and the drive shaft atdifferent mutual angular positions. This involves practically a newdesign for each application.

Mechanical linkages have been proposed by means of which it is possibleto form the eccentricity of the control point from the positioningtravel of both servo motors, even if only the speed lever or only thesteering wheel is actuated. Although the need to arrange the servomotors at a definite angle with respect to the longitudinal axis of theship is eliminated thereby, mechanical linkages which are difficult toaccommodate are required between the command post such as, for example,the bridge, and the cycloid propeller, which is usually a great distanceaway.

The maximum permissible value of th'eeccentricity for the speed isderived from the :selected eccentricity for the steering thrust, wherethe resultantof the eccentricities, taking into consideration thepermissible load on the drive motor, describes a figure similar to anellipse.

Furthermore, the proposed mechanical control linkage only permits therealization of specific definite interdependencies of steering andspeedcontrol commands. The control is also sensitive to acceleration and mustbe constructed for each propeller size from components of differentsize. This results in relatively high costs, since mass production isimpossible.

An object of our invention is to create a control for a cycloidpropeller in which the advantageous properties of the proposed controlmay be attained without the burden of their shortcomings.

An object of the invention is to provide a control system for a cycloidpropeller which may utilize massproduced, non-moving parts, which may bethe same for any propeller size, to provide with great accuracy adesired interdependency of the control point eccentricities for thetravel thrust and the rudder force.

Another object of the invention is to provide a control system for acycloid propeller which does not require special runs.

Another object of the invention is to provide a control system for acycloid propeller which is largely free of wear, insensitive to shockand suitable for connection to automatic steering installations.

in accordance with the invention, control connection is establishedbetween the speed control lever and the steering wheel and the servomotors, each via an electrical signal transmitter. The signal of thetransmitter associated with the speed control lever is controlled as afunction of a function generator supplied by the transmitter of thesteering wheel. in this manner, it is possible, by using mass-produced,non-moving parts, especially electronic components, which may be thesame for cycloid propellers of any size, to bring into a desiredinterdepencey with each other, with great accuracy, the control pointeccentricities for the travel thrust and the rudder force. Special runsare therefore no longer necessary. The control of our invention isfurthermore largely free of wear, insensitive to shock, and is suitablefor connection to automatic steering installations. The control of theinvention maybe combined with additional control circuits.

in accordance with the invention, a control system for a cycloidpropeller having pivoted blades having a control point, first and secondservo motors, a speed control lever controlling the first servo motorand a steering wheel controlling the second servo motor to adjust theposition of the control point of the blades in two directions comprises.a first control connection between the lever and the first servo motor.The first control connection includes a first signal transmitter forproducing a first signal. A second control connection is providedbetween the wheel and the second servo motor. The second controlconnection includes a second signal transmitter for producing a secondsignal. A function generator controls the first signal as a function ofthe function generator. The second signal is supplied to the functiongenerator.

The first control connection includes a multiplier having one inputconnected to the first signal transmitter and another input coupled tothe second signal transmitter via the function generator.

Each of the first and second servo motors has an axis and the bladeshave a direction of eccentricities for a straight ahead course. Thefirst control connection includes computer means and the second controlconnection includes computer means, for'computing the relations xcosy+ysin'yand xsiny+ycosy wherein y is the angle between the axis of one ofthe first and second servo motors and the direction of eccentricitiesfor a straight ahead course.

In order that the invention may be readily carried into effect, it willnow be described with reference to the accompanying drawings, wherein:

FIG. 1 is a block diagram of an embodiment of the controlsystem of theinvention with the cycloid propeller illustrated schematically;

FIG. 2 is a schematic side view, partly in section, of a cycloidpropeller;

FIG. 3 is a block diagram of another embodiment of the control system ofthe invention; and

FIG. 4 is a block diagram of still another embodiment of the controlsystem of the invention.

In FIG. 1, a cycloid propeller la has a driven wheel structure 6 havingpivoted blades 2 to and is rotatably installed at the bottom of a vessel1 (FIG. 2). The wheel structure may rotate about an axis of rotation Aand is driven by a drive motor 8 via a gear drive 7 (FIG. 2). Pivot pins9 of the pivoted blades 2 to 5 are supported in holes of the wheelstructure 6 and are guided during their rotation by a crank drive 10 insuch a manner that a perpendicular erected in the axis of rotation onthe contour surface of the pivoted blade extends approximately through acontrol point S. As shown in FIG. 2, the crank drive 10 constitutes, forpractical purposes, a blade drive linkage 10a which is hinged at thecontrol point S and is connected to the pivot pin 9.

In order to change the speed and the rudder angle, the control point Sis positioned by two mutually perpendicular servo motors l2 and 13 via acontrol stick 11 into a position S, which is eccentric to the axis ofrotation A of the wheel structure 6, shown by broken lines. By geometricaddition of the positioning travel of the two servo motors l2 and 13,thrust forces at any desired angle relative to the ships axis may beobtained. The ship may thereby be moved in any direction.

In the control system of the invention, a speed control lever 14 has acorresponding first electrical signal transmitter 15 which is connectedin a first control connection, via an input 16 of a multiplier 18, tothe first servo motor 12. A second input 17 of the multiplier 18 isconnected via a function generator 19 to the output 21a of a secondelectrical signal transmitter 21 which is operated by a steering wheel20 and is connected in a second control connection to the second servomotor 13.

In loading of the drive motor 8, it is advantageous if the resultant Rof the eccentricities describes an ellipse, as show in FIG. 3. Toaccomplish this, the function generator 19 is designed so that itsoutput signal varies in dependence upon the rudder angle signal y,according to the function Vl y,,. In this manner, the control signal xfor the speed is computed from the control quantity y, for the ruddermotion and the quantity x preset by the speed control lever 14, whereapplies. In the control system of the invention, other relations, forexample, according to a parabolic function, may also be realized in asimple manner.

As shown in FIG. 3, in one embodiment of the invention, there areincluded in the first and second control connections between the speedcontrol lever 14 and the steering wheel 15 and the servo motors 12 and13, respectively, computers, particularly computer amplifiers 22, 23, 25and 26, and adders 24 and 27, for computing the relations In this mannerthe coordinate system of the servo motors l2 and 13 may be rotated byany desired angle relative to the eccentricities required for astraightahead course g. The servo motors l2 and 13 may thus be installedin any direction relative to the ships longitudinal axis, so that theposition relative to the drive shaft can always remain the same.Different designs of the housing therefore become unnecessary, and thedirections of the vectors may be adjusted subsequently on the completelyinstalled propeller by setting another angle into the computeramplifiers 22, 23, 25 and 26, corresponding to the actual conditions.

The servo motors l2 and 13 for adjusting the eccentricities areconnected in the first and second control connections or circuits andthe components and 1 are fed as reference values to the controls of thefirst and second servo motors, respectively. The actual value is formedin each case by the component R, and R,,, respectively, measured in thedirection of the respective servo motor, of the total eccentricity R(FIG. 1).

The control system of the invention has the following advantageousembodiments:

a. Power limitation for the drive motor:

A signal transmitter at the control rod of the injection pump of theDiesel engine used as the drive motor reduces the power consumption ofthe propeller to a predetermined value through eccentricity control inaccordance with the invention, with the interposition of computercircuitry.

b. Optimizing the speed of the drive motor by the eccentricity or bladeposition of the propeller:

By simultaneous control of the speed rotation adjustment and theeccentricity of the propeller from the speed transmitter via functiongenerators an optimum overall efficiency may be achieved for any load.

c. Call-up of programs for emergency maneuvers which are necessary, forexample, in the event of oil shortage or excessive heating of oil:

In extreme cases, recording sensors can cause a reduction of theeccentricity down to zero. In the case of extreme heeling, which ismeasured by a heeling sensor, eccentricities in the transverse directionmay be initiated automatically, which cause the ship to turn. Heelingmay also occur due to too much transverse pull of a tug or transversesea motion. The ship is turned automatically with her bow against theheeling angle, in the case of transverse sea motion, against the maximumheeling angle. The forward speed command is automatically set to zero.To initiate this emergency maneuver, the time derivative of the heelingangle may also be used, in addition to the angle itself.

d. Immediate utilization of ocean vessel guidance:

If there is remote control from the ocean-going vessel to the individualtugs withanswering provision, the commands may be given by theocean-going vessel, and only the maximum permissible limits, theso-called leeway, is continuously preset at the tug.

e. Optimization of deceleration and acceleration processes: a

The change in time of the pitch may be controlled by a timing circuit,the dynamics of which must be determined bysuitable tests, in such amanner that the permissible intermittent overload rating of the drivemotor is not exceeded and the flow at the blades does not separate. Thetiming circuit is influenced by the instantaneous overload capacity ofthe drive motor. This is adaptive control.

f. In order to keep a floating platform such as, for example, a drillingvessel or crane, in a given position, the eccentricities for thelongitudinal and transverse forces may be automatically controlled byposition sensors and gyros in such a manner that the forces suppliedcounteract the position deviation. This is dynamic positioning. Coursecontrol of a ship may readily be realized 'in a similar manner.

In the embodiment of FIG. 4, another control connection is included withthose of the aforedescribed embodiments. In FIG. 4, a function generator28 is supplied with input data comprising the ships speed v, measured bya speed measuring device 29, and the power P of the drive motor 8,measured by a power measuring device 30.

The function generator 28 calculates the relation between the shipsspeed v and the driving power P, as

input data, and the datum or reference speed n* of the drive motor v8,as well as the eccentricity of the propeller, as output data, whosetotal effectivenss or efficiency is a maximum. The datum or referencespeed data n* is supplied to a speed regulator 31 of the drive motor 8.The data e, of the eccentricity of the propeller is supplied to amultiplier 15a which is connected to the output of the first electricalsignal transmitter 15.

In a similar manner, it is possible to provide a control connectionaccording to the invention with other control or regulating circuits,for example, for direct utilization in ships or ocean-going vesselguidance,

during tug operation.

While the invention has been described bymeans of specific examples andin a specific embodiment, we do not wish to be limited thereto, forobvious modifications will occur to those skilled in the art withoutdeparting from the spirit and scope of the invention.

We claim:

1. A control system for a cycloid propeller having pivoted blades havinga control pint, first and second servo motors, a speed control levercontrolling the first servo motor and a steering wheel controlling thesecond servo motor to adjust the position of the control point of theblades in two directions, said control system comprising a first controlconnection between the lever and the first servo motor, controlconnection including a first signal transmitter for producing a firstsignal; a second control connection between the wheel and the secondservo motor, the second control connection including a second signaltransmitter for producing a second signal; a function generator forcontrolling the first signal as a function of the function generator;and means for supplying the second signal to the function generator.

2. A control system as claimed in claim 1, wherein the first controlconnection includes a multiplier having one input connected to the firstsignal transmitter and another input coupled to the second signaltransmitter via the function generator.

3. A control system as claimed in claim 1, wherein each of the first andsecond servo motors has an axis and the blades have a direction ofeccentricities for a straight ahead course, and wherein the firstcontrol connection includes computer means and the second controlconnection includes computer means for computing the relationsxcos'y-l-ysin'yand -xsin'y+ycos'y wherein 7 is the angle between theaxis of one of the first and second servo motors and the direction ofeccentricities for a straight ahead course.

4. A control system as claimed in claim 2, further comprising anothercontrol connection.

'0' I l l

1. A control system for a cycloid propeller having pivoted blades havinga control pint, first and second servo motors, a speed control levercontrolling the first servo motor and a steering wheel controlling thesecond servo motor to adjust the position of the control point of theblades in two directions, said control system comprising a first controlconnection between the lever and the first servo motor, controlconnection including a first signal transmitter for producing a firstsignal; a second control connection between the wheel and the secondservo motor, the second control connection including a second signaltransmitter for producing a second signal; a function generator forcontrolling the first signal as a function of the function generator;and means for supplying the second signal to the function generator. 2.A control system as claimed in claim 1, wherein the first controlconnection includes a multiplier having one input connected to the firstsignal transmitter and another input coupled to the second signaltransmitter via the function generator.
 3. A control system as claimedin claim 1, wherein each of the first and second servo motors has anaxis and the blades have a direction of eccentricities for a straightahead course, and wherein the first control connection includes computermeans and the second control connection includes computer means forcomputing the relations x cos gamma + y sin gamma and - x sin gamma + ycos gamma wherein gamma is the angle between the axis of one of thefirst and second servo motors and the direction of eccentricities for astraight ahead course.
 4. A control system as claimed in claim 2,further comprising another control connection.